1. Field of the Invention
This invention relates to fluid flow regulators and more particularly to such devices which automatically maintain a substantially constant rate of flow therethrough.
2. Background of the Invention
Flow regulators have been used for maintaining flow of fluids substantially constant despite changes in pressures upstream or downstream of the regulator. Such regulators usually include a spring, and the sole function of the spring is to bias a valve member in a manner to aid in regulating the rate of flow of fluids through the regulator.
U.S. Pat. No. 3,381,703 which issued to D. V. Chenoweth on May 7, 1968 teaches a fluid flow regulator having a spring which biases a sleeve valve toward open position. The sleeve valve carries an orifice plate. Flow through the orifice of the orifice plate creates a drop in pressure and tends to compress the spring and, at the same time, slide the slide valve toward closed position. The reduction in flow diminishes the pressure drop across the orifice plate. The spring reacts by expanding and sliding the valve toward open again. Thus, regulation of the flowing fluid is brought about.
U.S. Pat. No. 3,319,717 issued to D. V. Chenoweth on May 16, 1967 and teaches a system for injecting fluids into a plurality of separate zones in a well through use of a regulator device (like that of U.S. Pat. No. 3,381,708) for each zone.
U.S. Pat. No. 3,472,275 which issued to L. F. Castro et al on Oct. 14, 1969 teaches use of a regulator resembling that disclosed in U.S. Pat. No. 3,381,708 supra. It includes a spring, a valve, and orifice plate which function in about the same manner as do the spring, valve, and orifice plate of the regulator, the spring functioning solely to slide the valve toward open position.
There is not found in the known prior art a flow regulator wherein the flowing fluid passes between the coils of the spring but also through an orifice such that a pressure drop across the orifice compresses the spring, thus forcing its coils closer together, thus pinching and reducing the flow passing therebetween, the thus reduced flow causing a reduction in the pressure drop across the orifice and allowing the spring to expand to permit greater flow between its coils.
The present invention is directed to fluid flow regulators having a housing with a flow course therethrough, a coil spring in the flow course, a piston slidable in the housing and having an orifice therein, the piston having its downstream end abutting the upstream end of said spring, and the downstream end of said spring being closed whereby the stream of fluids flowing through the regulator is first restricted by the fixed orifice in the piston and the flow stream is restricted a second time by a variable restriction in that fluids passing through the fixed orifice lose a portion of their pressure and then are emptied into the coil spring, after which they flow outwardly through the gaps between the coils of the spring, the coils being held close together due to the pressure drop across the fixed orifice causing a displacement of the piston and a resultant compression of the spring which lessens the gaps to restrict the flow a second time to regulate the flow of fluids at a substantially constant rate.
It is therefore one object of this invention to provide an improved fluid flow regulator which regulates flow passing between the coils of a spring by varying the gap between adjacent coils thereof in response to a difference in pressure developed across an orifice in a piston operatively associated with the spring, the spring being compressed as a result of an increased pressure drop across the orifice, thus to force the spring coils closer together to further reduce the flow, and the spring being allowed to expand in response to a decrease in such drop in pressure across the orifice to increase the gap between adjacent spring coils and allow more flow to take place therethrough.
Another object is to provide a regulator wherein the spring is formed with rectangular wire.
Another object is to provide a regulator of the character described wherein the diameter of the piston is approximately equal to the internal diameter of the spring.
Another object is to provide such a regulator in which the piston is provided with a replaceable fixed orifice.
Another object is to Provide such a regulator adapted to be connected directly into a flow conduit.
Another object is to provide such a regulator which is adapted for use in a well flow conduit and/or which is installable in and removable from the well through use of wireline tools, or the like.
Another object is to provide a regulator of the character described in which its flow course terminates in a lateral port and which is adapted for use in side pocket mandrels in wells.
Other objects and advantages will become apparent from reading the description which follows and from studying the accompany drawing, wherein :